Fixed cutter drill bit having spherical cutter orienting system

ABSTRACT

A bit for drilling a wellbore includes: a shank having a coupling formed at an upper end thereof; a body mounted to a lower end of the shank; and a cutting face forming a lower end of the bit. The cutting face includes: a blade protruding from the body; a cutter including: a substrate mounted in a pocket formed in the blade; and a cutting table made from a superhard material, mounted to the substrate, and having a non-planar working face with a cutting feature; and a cutter orienting system (COS). The COS includes a knob mounted to or formed on a back face of the substrate; and a dimple formed in a back wall of the pocket and engaged with the knob. The dimple and the knob are positioned relative to the cutting feature to orient the cutting feature to an operative position.

BACKGROUND OF THE DISCLOSURE Field of the Disclosure

The present disclosure generally relates to a fixed cutter drill bit having a spherical cutter orienting system.

Description of the Related Art

U.S. Pat. No. 4,654,947 discloses a method and apparatus by which the cutting face of a drill bit is renewed. The drill bit has a cutting face including a plurality of radially spaced apart stud assemblies, each received within a socket. A polycrystalline diamond disc forms one end of the stud assembly. The socket is in the form of a counterbore extending angularly into the bit body so that when a marginal end of the stud assembly is forced into a socket, a portion of the face of the diamond disc extends below the bottom of the bit body for engagement with the bottom of a borehole. A passageway communicates with the rear of the counterbore and extends back to a surface of the bit. Fluid pressure is effected within the passageway, thereby developing sufficient pressure differential across the stud assembly to cause the stud assembly to move respective to the socket. This action forces a marginal end of the stud assembly to move sufficiently respective to the socket so that the free marginal end of the stud assembly can be grasped by a tool and manipulated in a manner to bring an unused cutting edge of the diamond disc into operative cutting relationship respective to the bottom of the bit. The reoriented stud assembly is forced back onto seated relationship respective to the socket. The stud assembly includes a circumferentially extending seal means which cooperates with the socket interior with a piston-like action.

U.S. Pat. No. 5,285,859 discloses a drill bit cutter structure and means of mounting said cutter structure relative to a drill bit for drilling earth formations in which the cutter structure provides diverse rotational orientation of the cutting element about at least one axis relative to the drill bit. The cutter structure generally includes a bearing surface associated with the drill bit, a supporting member articulable with the bearing surface to provide diverse orientation thereof, and a cutting element secured to said supporting member.

U.S. Pat. No. 7,070,011 discloses a steel body rotary drag bit for drilling a subterranean formation including a plurality of support elements affixed to the bit body, each forming at least a portion of a cutting element pocket. Each of a plurality of cutting elements has a substantially cylindrical body and is at least partially disposed within a cutter pocket. At least a portion of the substantially cylindrical body of each cutting element is directly secured to at least a portion of a substantially arcuate surface of the bit body. At least a portion of a substantially planar surface of each cutting element matingly engages at least a portion of a substantially planar surface of a support element.

U.S. Pat. No. 8,011,456 discloses a cutting element for use with a drill bit including a substrate having a longitudinal axis, a lateral surface substantially symmetric about the longitudinal axis and one or more key elements coupled to the lateral surface. The lateral surface lies between an insertion end and a cutting end of the substrate. The one or more key elements are substantially axially aligned with the longitudinal axis and configured to selectively rotationally locate the substrate in a pocket. A drill bit configured for retaining a cutting element having one or more key elements is also disclosed.

U.S. Pat. No. 8,132,633 discloses a self positioning cutter element and cutter pocket for use in a downhole tool having one or more cutting elements. The self positioning cutter element includes a substrate and a wear resistant layer coupled to the substrate. The cutter element includes a cutting surface, a coupling surface, and a longitudinal side surface forming the circumferential perimeter of the cutter element and extending from the cutting surface to the coupling surface. The cutter element has one or more indexes formed on at least a portion of the coupling surface. In some embodiments, the index also is formed on at least a portion of the longitudinal side surface. Hence, the coupling surface is not substantially planar. Additionally, at least a portion of the longitudinal side surface does not form a substantially uniform perimeter. The cutter pocket also is indexed to correspond and couple with the indexing of the cutter element.

U.S. Pat. No. 9,481,033 discloses an earth-boring tool including a body having at least one blade, and at least one cutting element recess may be formed in a surface of the at least one blade. At least one cutting element may be affixed within the at least one cutting element recess. The at least one cutting element may comprise a substantially cylindrical lateral side surface configured to allow the at least one cutting element to rotate about a longitudinal axis within the at least one cutting element recess when the at least one cutting element is partially inserted into the at least one cutting element recess. The at least one cutting element includes a back face comprising alignment features configured to abut complementary alignment features disposed on a back surface of the at least one cutting element recess.

US 2017/0058615 discloses a convex ridge type non-planar cutting tooth and a diamond drill bit, the convex ridge type non-planar cutting tooth including a cylindrical body, the surface of the end portion of the cylindrical body is provided with a main cutting convex ridge and two non-cutting convex ridges, the inner end of the main cutting convex ridge and the inner ends of the two non-cutting convex ridges converge at the surface of the end portion of the cylindrical body, the outer end of the main cutting convex ridge and the outer ends of the two non-cutting convex ridges extend to the outer edge of the surface of the end portion of the cylindrical body, the surfaces of the end portion of the cylindrical body on both sides of the main cutting convex ridge are cutting bevels. The convex ridge type non-planar cutting tooth and the diamond drill bit have great ability of impact resistance and balling resistance. According to the features of drilled formation, convex ridge type non-planar cutting teeth are arranged on the drill bit with different mode, which can improve the mechanical speed and footage of the drill bit.

SUMMARY OF THE DISCLOSURE

The present disclosure generally relates to a fixed cutter drill bit having a spherical cutter orienting system. In one embodiment, a bit for drilling a wellbore includes: a shank having a coupling formed at an upper end thereof; a body mounted to a lower end of the shank; and a cutting face forming a lower end of the bit. The cutting face includes: a blade protruding from the body; a cutter including: a substrate mounted in a pocket formed in the blade; and a cutting table made from a superhard material, mounted to the substrate, and having a non-planar working face with a cutting feature; and a cutter orienting system (COS). The COS includes a knob mounted to or formed on a back face of the substrate; and a dimple formed in a back wall of the pocket and engaged with the knob. The dimple and the knob are positioned relative to the cutting feature to orient the cutting feature to an operative position.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the above recited features of the present disclosure can be understood in detail, a more particular description of the disclosure, briefly summarized above, may be had by reference to embodiments, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only typical embodiments of this disclosure and are therefore not to be considered limiting of its scope, for the disclosure may admit to other equally effective embodiments.

FIGS. 1A-1D illustrate manufacture of an alloy body of a fixed cutter drill bit having a spherical cutter orienting system (SCOS), according to one embodiment of the present disclosure.

FIG. 2A illustrates a typical leading cutter pocket of the drill bit with a dimple of the SCOS. FIGS. 2B-2D illustrate a shaped cutter having knobs of the SCOS.

FIGS. 3A-3D illustrate brazing of the shaped cutter into the pocket and engagement of the knobs with the dimples.

FIG. 4 illustrates the completed drill bit.

FIGS. 5A-5C illustrate a mold of a casting assembly for manufacture of a matrix body fixed cutter drill bit having the SCOS, according to another embodiment of the present disclosure.

FIGS. 6A and 6B illustrate a typical leading cutter displacement of the casting assembly. FIG. 6C illustrates installation of the cutter displacement into a displacement pocket of the mold.

FIG. 7A illustrates the casting assembly. FIG. 7B illustrates the casting assembly placed in a furnace for melting binder thereof.

FIG. 8A illustrates a typical leading cutter pocket of the matrix drill bit. FIG. 8B illustrates the infiltrated body of the matrix drill bit.

FIGS. 9A-9C illustrate brazing of the shaped cutter into the pocket and engagement of the knobs with the dimples.

FIGS. 10A and 10B illustrate a second shaped cutter for use with the SCOS, according to another embodiment of the present disclosure. FIGS. 10C and 10D illustrate a third shaped cutter for use with the SCOS, according to another embodiment of the present disclosure.

FIGS. 11A and 11B illustrate a fourth shaped cutter and knobs of a second SCOS, according to another embodiment of the present disclosure. FIG. 11C illustrates a knob of a third SCOS, according to another embodiment of the present disclosure. FIG. 11D illustrates a sixth shaped cutter for use with the SCOS, according to another embodiment of the present disclosure.

DETAILED DESCRIPTION

FIGS. 1A-1D illustrate manufacture of an alloy body 2 of a fixed cutter drill bit 1 (FIG. 4) having a spherical cutter orienting system (SCOS) 3 (FIG. 3D), according to one embodiment of the present disclosure. FIG. 2A illustrates a typical leading cutter pocket 4 of the drill bit 1 with a dimple 3 d of the SCOS 3. Referring specifically to FIG. 1A, a piece of round stock 5 may be received from a metalworking plant. The round stock 5 may be made from an alloy, such as steel. The round stock 5 may be mounted in a computer numerical control (CNC) machine tool 6.

Referring specifically to FIG. 1B, the round stock 5 may be turned in the tool 6 to form a lap coupling adjacent to a mounting end thereof. The round stock 5 may be further turned in the tool 6 to form a bore (not shown) therein extending from the mounting end and a plenum (not shown) therein extending from the bore. The round stock 5 may be further turned in the tool 6 to form a taper 7 in an outer surface thereof adjacent to the lap coupling. The round stock 2 may be further turned in the tool 6 to form an inner cone 8 c (numbered in FIG. 4) in a cutting face thereof, an outer shoulder 8 s in the cutting face, and an intermediate nose 8 n between the cone and the shoulder. The cutting face may be located at an end of the round stock 5 opposite to the mounting end. The round stock with the turned features will now be referred to as a blank.

The tool 6 may then be operated to mill fluid courses in the cutting face of the blank, thereby forming a plurality of blades 9 between adjacent fluid courses. The tool 6 may be further operated to drill a plurality of ports 23 (FIG. 3A) into the blank. The ports 23 may extend from the fluid courses and to the plenum of the blank. The tool 6 may also be operated to mill junk slots in an outer surface of the blank, thereby forming a plurality of gage pads 10 between adjacent junk slots. Each gage pad 10 may extend from a respective blade 9 to a respective taper 7 and each junk slot may extent from a respective fluid course to the lap coupling. The gage pads 10 may extend along the body 2 generally longitudinally with a slight helical curvature. The gage pads 10 and junk slots may form a gage section and may define an outer portion of the drill bit 1.

The blades 9 may include one or more primary blades 9 p (numbered in FIG. 4) and one or more secondary blades 9 s. The blades 9 may be spaced around the cutting face and may protrude from a bottom and side of the body 2. The primary blades 9 p may each extend from a center of the cutting face to the shoulder 8 s. The primary blades 9 p may extend generally radially along the cone 8 c and nose 8 n with a slight spiral curvature and generally longitudinally along the shoulder 8 s with a slight helical curvature. One or more of the ports 23 may be disposed adjacent to the center of the cutting face. The secondary blades 9 s may each extend from a location on the cutting face adjacent to a respective inner port to the shoulder 8 s. The secondary blades 9 s may extend generally radially along the nose 8 n with a slight spiral curvature and generally longitudinally along the shoulder 8 s with a slight helical curvature. Since the blades 9 are formed integrally with the body 2, the blades are also made from the same material as the body.

Referring specifically to FIG. 2A, the CNC machine tool 6 may be further operated to mill a row of leading cutter pockets 4 along a leading edge of each blade 9. For the primary blades 9 p, each row of leading cutter pockets 4 may extend from the center of the cutting face to a shoulder end of the respective blade. For the secondary blades 9 s, each row of leading cutter pockets 4 may extend from the location adjacent to the respective inner port to a shoulder end of the respective blade. Each leading cutter pocket 4 may be shaped to receive a substrate 17 (FIG. 2B) of a respective shaped cutter 15. Each leading cutter pocket 4 may be defined by a curved sidewall 4 s and a flat back wall 4 b.

The CNC machine tool 6 may be further operated to mill a row of backup pockets along portions of the blades 9 in the shoulder section 8 s. Each row of backup pockets may extend into portions of the blades 9 in the nose section 8 n. Each backup pocket may be aligned with or slightly offset from a respective leading cutter 15. The CNC machine tool 6 may be further operated to mill one or more stud pockets in each primary blade 9 p at a bottom of a portion thereof in the cone section 8 c. The stud pockets may each be in a backup position relative to a respective leading cutter pocket 4 and may be aligned with or slightly offset from the respective leading cutter 15.

Referring specifically to FIGS. 1C and 2A, the CNC machine tool 6 may be further operated to mill a set of one or more, such as three, dimples 3 d extending from each leading cutter pocket 4 into the respective blade 9. Each set of dimples 3 d may be located along the back wall 4 b of the respective cutter pocket 4. Each dimple 3 d may be hemi-spherical.

Referring specifically to FIG. 1D, the body 2 may be removed from the tool 6 and delivered to a welding station (not shown). A shank 12 having a lap coupling may be assembled with the lap coupling of the body 2 and the connection therebetween secured by a weld. The shank 12 may have a threaded coupling, such as a pin, formed at an end opposite to the lap coupling for assembly as part of a drill string (not shown).

Alternatively, threaded couplings may be used to connect the body 2 and the shank 12. Alternatively, the shank may also be formed from the round stock 5 using the tool 6, thereby resulting in monoblock body 2 and shank 12.

The body 2 and shank 12 may be moved from the welding station and mounted in a laser cladding machine 13. The laser cladding machine 13 may be operated to deposit hardfacing 14 onto the blades 9 and gage pads 10 to increase resistance thereof to abrasion and/or erosion. The hardfacing 14 may be ceramic or cermet, such as a carbide or carbide cemented by metal or alloy. The hardfacing 14 may be deposited on a portion of a leading face, a portion of a trailing face, and a bottom/outer surface of each blade 9. The hardfaced portions of the leading and trailing faces may extend from the leading and trailing edges of each blade 9 to or past mid-portions thereof. The pockets 4 may be masked from the hardfacing 14. The hardfacing 14 may be deposited on a portion of a leading face, a portion of a trailing face, and an outer surface of each gage pad 10.

FIGS. 2B-2D illustrate a shaped cutter having knobs 3 k of the SCOS 3. The shaped cutter 15 may include a non-planar cutting table 16 mounted to a cylindrical substrate 17. The cutting table 16 may be made from a superhard material, such as polycrystalline diamond, and the substrate 17 may be made from a hard material, such as a cermet, thereby forming a compact, such as a polycrystalline diamond compact. The cermet may be a cemented carbide, such as a group VIIIB metal-tungsten carbide. The group VIIIB metal may be cobalt.

The cutting table 16 may have an interface 18 with the substrate 17 at a rear end thereof and a non-planar working face at a front end thereof. The substrate 17 may have the interface 18 at a front end thereof and a rear end for being received in the leading cutter pocket 4. The rear end of the substrate 17 may have an outer chamfered edge 17 e formed in a periphery thereof and a back face 17 b opposite from the interface 18.

The working face may have a plurality of recessed bases, a plurality of protruding ribs, and an outer chamfered edge 16 e. The bases may be located between adjacent ribs and may each extend inward from a side 16 s of the cutting table 16. Each rib may extend radially outward from a center 16 c of the cutting table 16 to the side 16 s. Each rib may be spaced circumferentially around the working face at regular intervals, such as at one-hundred twenty degree intervals. Each rib may have a ridge 19 a-c and a pair of bevels each extending from the ridge to an adjacent base.

The substrate 17 may have a knob 3 k mounted to the back face 17 b for each ridge 19 a-c. Each knob 3 k may be formed separately from the rest of the cutter 15 and then mounted to the substrate 17 thereof, such as by brazing. Each knob 3 k may be angularly offset from the associated ridge 19 a-c, such as being located opposite therefrom. Each knob 3 k may be hemi-spherical and have a diameter ranging between twenty-five and forty-five percent of a diameter of the back face 17 b. The knobs 3 k may be spaced about the back face 17 b at regular intervals, such as at one-hundred twenty degree intervals. The dimples 3 d may be sized and arranged about the back wall 4 b of the pocket 4 to mate with the knobs 3 k. The knobs 3 k and dimples 3 d may be arranged to mate in any of three different orientations of the cutter 15. Peripheries of the knobs 3 k and dimples 3 d may be slightly spaced apart and centers of the knobs and dimples may be located on corners of an equilateral triangle (not shown). Each knob 3 k may be made from the same material as the substrate or a different material than the substrate, such as a metal or alloy, such as steel.

Alternatively, each knob 3 k may be formed integrally with the substrate 17 during formation of the substrate 17 or during high pressure high temperature sintering of the cutter 15. Alternatively, each knob 3 k may be formed integrally with the substrate 17 after formation of the rest of the cutter 15 by machining the knobs into the back face 17 b.

FIGS. 3A-3D illustrate brazing of the shaped cutter 15 into the pocket 4 and engagement of the knobs 3 k with the dimples 3 d. The body 2 and shank 12 may be moved from the laser cladding machine 13 to a cutter station. The cutter station may be manual or automated. The shaped cutters 15 may be mounted in the leading cutter pockets 4 of the blades 9. Each cutter 15 may be delivered to the respective pocket 4 by an articulator 21. The articulator 21 may retain the shaped cutter 15 only partially in the pocket 4 such that the knobs 3 k and the dimples 3 d do not engage.

Once delivered, a second braze material 20 may be applied to an interface formed between the respective pocket 4 and the cutter 15 using an applicator 22. As the second braze material 20 is being applied to the interface, the articulator 21 may rotate the shaped cutter 15 relative to the pocket 4 to distribute the second braze material 20 throughout the interface. The articulator 21 may then be operated to align the knobs 3 k with the dimples 3 d and engage the aligned members, thereby ensuring that the shaped cutter 15 is properly oriented within the respective pocket 4 to an operative position. The operative position may be that the operative ridge 19 a is perpendicular to a projection 24 of the leading edge of the respective blade 9 through the leading cutter pocket 4.

A heater (not shown) may then be operated to melt the second braze material 20. Cooling and solidification of the braze material 20 may mount the cutter 15 to the respective blade 9. The brazing operation may then be repeated until all of the shaped cutters 15 have been mounted to the respective blades 9. The brazing operation may also be repeated for mounting the backup cutters and studs into the backup pockets and stud pockets. Once the cutters 15 have been mounted to the respective blades 9, a nozzle (not shown) may be inserted into each port 23 and mounted to the body 2, such as by screwing the nozzle therein.

Alternatively, the second braze material 20 may be heated by a torch while the cutter is being articulated.

A first braze material 11 used to mount the knobs 3 k to the substrate 17 may have a greater liquidus temperature than the second braze material 20 used to mount the cutters 15 to the blades 9 so that the knobs 2 k are not de-brazed from the substrates 17 while the cutters 15 are being mounted to the blades. The first liquidus temperature may be ten percent, twenty percent, thirty percent forty percent, or fifty percent greater than the second liquidus temperature. Each braze material 11, 20 may be a metal or alloy.

Each backup cutter may include a cutting table mounted to a cylindrical substrate. The cutting table may be made from a superhard material, such as polycrystalline diamond, and the substrate may be made from a hard material, such as a cermet, thereby forming a compact, such as a polycrystalline diamond compact. The cermet may be a cemented carbide, such as a group VIIIB metal-tungsten carbide. The group VIIIB metal may be cobalt. Each stud may be made from a cermet.

FIG. 4 illustrates the completed drill bit 1. In use (not shown), the drill bit 1 may be assembled with one or more drill collars, such as by threaded couplings, thereby forming a bottomhole assembly (BHA). The BHA may be connected to a bottom of a pipe string, such as drill pipe or coiled tubing, thereby forming a drill string. The BHA may further include a steering tool, such as a bent sub or rotary steering tool, for drilling a deviated portion of the wellbore. The pipe string may be used to deploy the BHA into the wellbore. The drill bit 1 may be rotated, such as by rotation of the drill string from a rig (not shown) and/or by a drilling motor (not shown) of the BHA, while drilling fluid, such as mud, may be pumped down the drill string. A portion of the weight of the drill string may be set on the drill bit 1. The drilling fluid may be discharged by the nozzles and carry cuttings up an annulus formed between the drill string and the wellbore and/or between the drill string and a casing string and/or liner string.

Upon retrieval of the drill bit 1 from the wellbore, the drill bit may be inspected for wear. Should a wear flat be observed on any of the leading cutters 15, the worn cutter may be de-brazed from the respective leading cutter pocket 4 and rotated, such as by one-hundred twenty degrees, so that one of the unused ridges 19 b,c is moved to the operative position and then the knobs 3 k and dimples 3 d reengaged during re-brazing thereof, thereby extending the service life of the cutters 15.

FIGS. 5A-5C illustrate a mold 25 of a casting assembly 26 (FIG. 7A) for manufacture of a matrix body fixed cutter drill bit (not completely shown) having the SCOS 3, according to another embodiment of the present disclosure. FIGS. 6A and 6B illustrate a typical leading cutter displacement 28 of the casting assembly 26. FIG. 6C illustrates installation of the cutter displacement 28 into a displacement pocket 29 of the mold 25. FIG. 7A illustrates the casting assembly 26.

The casting assembly 26 may include the thick-walled mold 25, one or more displacements, such as the leading cutter displacements 28, a stalk 30 and one or more port displacements 31, a funnel 32, and a binder pot 33. Each of the mold 25, the displacements 28, 30, 31, the funnel 32, and the binder pot 33 may be made from a refractory material, such as graphite. The mold 25 may be fabricated with a precise inner surface forming a mold chamber using a CAD design model (not shown). The precise inner surface may have a shape that is a negative of what will become the facial features of the matrix drill bit.

The mold 25 may be fabricated with a displacement pocket 29 for each leading cutter pocket 34 (FIG. 8A) of the matrix drill bit. Each displacement pocket 29 may be shaped to receive a rear portion of the respective leading cutter displacement 28. Each displacement pocket 29 may be defined by a flat back wall 29 b, an access groove 29 g, a curved ledge 29 d, and a keyway 29 w. The keyway 29 may be formed in the back wall 29 b adjacent to an edge thereof. The ledge 29 d may extend from the back wall 29 b and the groove 29 g may be formed in the ledge adjacent to the edge of the back wall 29 b. Each keyway 29 w may include a semi-cylindrical mid-section and a pair of quarter-spherical end-sections.

Each leading cutter displacement 28 may be cylindrical having a rear face 28 r for insertion into the displacement pocket 29, a front face 28 f for extension into the mold chamber, and a side 28 s extending between the faces. Each leading cutter displacement 28 may also have a key 28 k protruding from the rear face 28 r adjacent to an edge of the rear face. The key 28 k may be formed as an integral part of the displacement 28 and may include a semi-cylindrical mid-section and a pair of quarter-spherical end-sections for mating engagement with the keyway 29 w.

Each leading cutter displacement 28 may also have a set of dimple-formers 28 m formed therein. The dimple-formers 28 m may be located at an edge of the front face 28 f and may extend therefrom along a portion of the side 28 s. Each dimple-former 28 m may be hemi-spherical and have a diameter corresponding to that of the respective knob 3 k, such as equal to or slightly greater than. The dimple-formers 28 m may be spaced about the front face 28 f at regular intervals, such as at one-hundred twenty degree intervals. Peripheries of the dimple-formers 28 m may be slightly spaced apart and centers of the dimple-formers may be located on corners of an equilateral triangle (not shown). A first one of the dimple-formers 28 m may be angularly offset from the key 28 k, such as being located opposite therefrom.

Each leading cutter displacement 28 may be aligned and inserted into the respective displacement pocket 29 such that the key 28 k mates with the keyway 29 w and mounted therein, such as by adhesive. The leading cutter displacements may be removed after infiltration to form the leading cutter pockets 34 in blades 36 (FIG. 8B) of the matrix drill bit for receiving respective shaped cutters 15. The port displacements 31 may be positioned adjacent to a bottom of the mold chamber and mounted to the mold. The stalk 30 may be positioned and mounted within the center of the mold chamber adjacent to a top of the port displacements 31. The stalk 30 may be removed after infiltration to form a bore 35 b and plenum 35 p (FIG. 8B) of the matrix drill bit. The port displacements 31 may be removed after infiltration to form respective ports 35 n (FIG. 8B) of the matrix drill bit.

The casting assembly 26 may further include a plurality of backup cutter displacements (not shown) disposed adjacent to the bottom of the mold chamber and the backup cutter displacements may be removed after infiltration to form backup pockets in the blades 36 of the matrix drill bit for receiving respective backup cutters (FIG. 9A). The casting assembly 26 may further include a plurality of stud displacements (not shown) disposed adjacent to the bottom of the mold chamber and the stud displacements may be removed after infiltration to form pockets in the blades of the matrix drill bit for receiving respective studs (not shown).

Once the displacements 28, 30, 31 have been placed into the mold 25, a blank 37 may be placed within the casting assembly 25. The blank 37 may be tubular and may be made from an alloy, such as steel. The blank 37 may be centrally suspended within the mold 25 around the stalk 30 so that a bottom of the blank is adjacent to a bottom of the stalk. Once the displacements 28, 30, 31 and the blank 37 have been positioned within the mold 25, body powder 38 b may be loaded into the mold to fill most of the mold chamber. The loading may include pouring of the body powder 38 b into the mold 25 while compacting thereof, such as by vibrating the mold. The body powder 38 b may be a ceramic, a cermet, or a mixture of a ceramic and a cermet. The ceramic may be a carbide, such as tungsten carbide, and may be cast and/or macrocrystalline. The cermet may include a carbide, such as tungsten carbide, cemented by a metal or alloy, such as cobalt.

Once loading of the body powder 38 b has finished, shoulder powder 38 s may be loaded into the mold 25 onto a top of the body powder to fill the remaining mold chamber. The shoulder powder 38 s may be a metal or alloy, such as the metal component of the ceramic of the body powder 38 b. For example, if the body powder is tungsten carbide ceramic and/or tungsten carbide-cobalt cermet, then the shoulder powder 38 s would be tungsten.

Once loading of the shoulder powder 38 s has finished, the binder pot 33 may be rested atop the funnel 32 and may be connected thereto, such as by a lap joint. The binder pot 33 may have a cavity formed therein and a sprue formed through a bottom thereof providing communication between the cavity and the funnel chamber. Binder 39 may then be placed into the cavity and through the sprue of the binder pot 33. The binder 39 may be in the form of pellets or chunks. The binder 39 may be an alloy, such as a copper based alloy. Once the binder 39 has been placed into the binder pot 33, flux (not shown) may be applied to the binder for protection of the binder from oxidation during infiltration.

FIG. 7B illustrates the casting assembly 26 placed in a furnace 40 for melting binder 39 thereof. The furnace 40 may include a housing 40 h, a heating element 40 e, a controller, such as programmable logic controller (PLC) 40 c, a temperature sensor 40 t, and a power supply (not shown). The furnace 40 may be preheated to an infiltration temperature. The casting assembly 26 may be inserted into the furnace 40 and kept therein for an infiltration time 40 m. As the casting assembly 26 is heated by the furnace 40, the binder 39 may melt and flow into the powders 38 b,s through the sprue of the binder pot 33. The molten binder may infiltrate powders 38 b,s to fill interparticle spaces therein. A sufficient excess amount of binder 39 may have been loaded into the binder pot 33 such that the molten binder fills a substantial portion of the funnel volume, thereby creating pressure to drive the molten binder into the powders 38 b,s.

FIG. 8A illustrates a typical leading cutter pocket 34 of the matrix drill bit. FIG. 8B illustrates the infiltrated body 41 of the matrix drill bit. Once the binder 39 has infiltrated the powders 38 b,s, the casting assembly 26 may be controllably cooled, such as by remaining in the furnace 40 with the heating element 40 e shut off. Upon cooling, the binder 39 may solidify and cement the particles of the powders 38 b,s together into a coherent matrix body 41. The binder 39 may also bond the body 41 to the blank 37. Once cooled, the casting assembly 26 may be removed from the furnace 40. The mold 25, funnel 32, and binder pot 33 may then be broken away from the body 41. A thread may be formed in an inner surface of the upper portion of the blank 37 and a threaded tubular extension screwed therein, thereby forming the shank 42. The threaded connection between the extension and the blank 37 may be secured by a weld.

Each leading cutter pocket 34 may be shaped to receive the substrate 17 of the respective shaped cutter 15. Each leading cutter pocket 34 may be defined by a curved sidewall 34 s and a flat back wall 34 b and have the set of dimples 3 d formed in the back wall by the dimple-former 28 m.

FIGS. 9A-9C illustrate brazing of the shaped cutter 15 into the pocket 34 and engagement of the knobs 3 k with the dimples 3 d. The matrix body 41 and shank 42 may be moved to the cutter station. The shaped cutters 15 may be mounted in the leading cutter pockets 34 of the blades 36. Each cutter 15 may be delivered to the respective pocket 34 by the articulator 21. The articulator 21 may retain the shaped cutter 15 only partially in the pocket 34 such that the knobs 3 k and dimples 3 d do not engage.

Once delivered, the second braze material 20 may be applied to an interface formed between the respective pocket 34 and the cutter 15 using the applicator 22. As the second braze material 20 is being applied to the interface, the articulator 21 may rotate the shaped cutter 15 relative to the pocket 34 to distribute the second braze material throughout the interface. The articulator 21 may then be operated to align the knobs 3 k with the dimples 3 d and engage the aligned members, thereby ensuring that the shaped cutter 15 is properly oriented within the respective pocket 4 to the operative position.

A heater (not shown) may then be operated to melt the second braze material 20. Cooling and solidification of the second braze material 20 may mount the cutter 15 to the respective blade 36. The brazing operation may then be repeated until all of the shaped cutters 15 have been mounted to the respective blades 36. The brazing operation may also be repeated for mounting the backup cutters and studs into the backup pockets and stud pockets. Once the cutters 15 have been mounted to the respective blades 36, a nozzle (not shown) may be inserted into each port 35 n and mounted to the matrix body 41, such as by screwing the nozzle therein.

Alternatively, the second braze material 20 may be heated by a torch while the cutter is being articulated.

FIGS. 10A and 10B illustrate a second shaped cutter 43 for use with the SCOS 3, according to another embodiment of the present disclosure. The second shaped cutter 43 may include a non-planar cutting table 44 mounted to a cylindrical substrate 45. The cutting table 44 may be made from a superhard material, such as polycrystalline diamond, and the substrate 45 may be made from a hard material, such as a cermet, thereby forming a compact, such as a polycrystalline diamond compact. The cermet may be a cemented carbide, such as a group VIIIB metal-tungsten carbide. The group VIIIB metal may be cobalt.

The cutting table 44 may have an interface 46 with the substrate 45 at a rear end thereof and the working face at a front end thereof. The working face may have a plurality of recessed bases 47 a-c, a protruding center section 48, a plurality of protruding ribs 49 a-c, and an outer edge. Each base 47 a-c may be planar and perpendicular to a longitudinal axis of the second shaped cutter 43. The bases 47 a-c may be located between adjacent ribs 49 a-c and may each extend inward from a side of the cutting table 44. The outer edge may extend around the working face and may have constant geometry. The outer edge may include a chamfer located adjacent to the side and a round located adjacent to the bases 47 a-c and ribs 49 a-c.

Each rib 49 a-c may extend radially outward from the center section 48 to the side. Each rib 49 a-c may be spaced circumferentially around the working face at regular intervals, such as at one-hundred twenty degree intervals. Each rib 49 a-c may have a triangular profile formed by a pair of curved transition surfaces, a pair of linearly inclined side surfaces, and a round ridge. Each transition surface may extend from a respective base 47 a-c to a respective side surface. Each ridge may connect opposing ends of the respective side surfaces. An elevation of each ridge may be constant (shown), declining toward the center section, or inclining toward the center section.

An elevation of each ridge may range between twenty percent and seventy-five percent of a thickness of the cutting table 44. A width of each rib 49 a-c may range between twenty and sixty percent of a diameter of the cutting table 44. A radial length of each rib 49 a-c from the side to the center section 48 may range between fifteen and forty-five percent of the diameter of the cutting table 44. An inclination of each side surface relative to the respective base 47 a-c may range between fifteen and fifty degrees. A radius of curvature of each ridge may range between one-eighth and five millimeters or may range between one-quarter and one millimeter.

The center section 48 may have a plurality of curved transition surfaces, a plurality of linearly inclined side surfaces, and a plurality of round edges. Each set of the features may connect respective features of one rib 49 a-c to respective features of an adjacent rib along an arcuate path. The elevation of the edges may be equal to the elevation of the ridges. The center section 48 may further have a plateau formed between the edges. The plateau may have a slight dip formed therein.

The substrate 45 may have the interface 46 at a front end thereof and a rear end for being received in either leading cutter pocket 4, 34. The substrate front end may have a planar outer rim, an inner mound for each rib 49 a-c, and a shoulder connecting the outer rim and each inner mound. A shape and location of the mounds may correspond to a shape and location of the ribs 49 a-c and a shape and location of the outer rim may correspond to a shape and location of the bases 47 a-c except that the mounds may not extend to a side of the substrate 45. Ridges of the mounds may be slightly above the bases 47 a-c (see dashed line in FIG. 10B). A height of the mounds may be greater than an elevation of the ribs 49 a-c. Similar to that discussed above for the substrate 17, the substrate 45 may have one of the knobs 3 k mounted to a back face thereof for each ridge of the respective rib 49 a-c.

Alternatively, a ridge of each mound may be level with or slightly below the bases 47 a-c.

FIGS. 10C and 10D illustrate a third shaped cutter 50 for use with the SCOS 3, according to another embodiment of the present disclosure. The third shaped cutter 50 may include a concave cutting table 51 mounted to a cylindrical substrate 52. The cutting table 51 may be made from a superhard material, such as polycrystalline diamond, and the substrate may be made from a hard material, such as a cermet, thereby forming a compact, such as a polycrystalline diamond compact. The cermet may be a cemented carbide, such as a group VIIIB metal-tungsten carbide. The group VIIIB metal may be cobalt.

The cutting table 51 may have an interface 53 with the substrate 52 and a working face opposite to the interface. The working face may have an outer chamfered edge, a planar rim adjacent to the chamfered edge, a conical surface adjacent to the rim, and a central crater adjacent to the conical surface. The interface 53 may have a planar outer rim and an inner parabolic surface. The thickness of the cutting table 51 may be a minimum at the crater and increase outwardly therefrom until reaching a maximum at the rim. A depth of the concavity may range between four percent and eighteen percent of a diameter of the third shaped cutter 50. Similar to that discussed above for the substrate 17, the substrate 52 may have the knobs 3 k mounted to a back face thereof. Since the third shaped cutter 50 is symmetric, the SCOS 3 may be used as an indexing system (should the cutter develop a wear flat) instead of an orienting system.

Alternatively, the cutting table 51 and substrate 52 may each be elliptical instead of circular. The SCOS 3 may then be used to orient the major or minor axis of the elliptical alternative cutter to the proper orientation. Alternatively, the cutting table 51 may each be circular or elliptical and have asymmetric curvature along different axes thereof. The SCOS 3 may then be used to orient the different axes of the asymmetrical alternative cutter to the proper orientation.

FIGS. 11A and 11B illustrate a fourth shaped cutter 54 and knobs 59 of a second SCOS, according to another embodiment of the present disclosure. The fourth shaped cutter 54 may include a non-planar cutting table 55 mounted to a cylindrical substrate 56. The cutting table 55 may be made from a superhard material, such as polycrystalline diamond, and the substrate 56 may be made from a hard material, such as a cermet, thereby forming a compact, such as a polycrystalline diamond compact. The cermet may be a cemented carbide, such as a group VIIIB metal-tungsten carbide. The group VIIIB metal may be cobalt.

The cutting table 55 may have an interface 57 with the substrate 56 at a rear end thereof and the working face at a front end thereof. The working face may have an outer edge and a ridge 58 protruding a height above the substrate and at least one recessed region extending laterally away from the ridge 58. The ridge 58 may be centrally located in the working face and extend across the working face. The presence of the ridge 58 may result in the outer edge undulating with peaks and valleys. The portion of the ridge 58 adjacent to the outer edge may be an operative portion. Since the ridge 58 extends across the working surface, the ridge may have two operative portions. The working face may further include a pair of recessed regions continuously decreasing in height in a direction away from the ridge 58 to the outer edge that is the valley of the undulation thereof. The ridge 58 and recessed regions may impart a parabolic cylinder shape to the working face. The outer edge of the cutting table 55 may be chamfered (not shown).

The substrate 56 may include a pair of knobs 59 mounted thereto, one knob for each operative portion of the ridge 58. Each knob 59 may be located on the back face of the substrate 56. Each knob 59 may be angularly offset from the associated operative portion, such as being located opposite therefrom. The knobs 59 may be similar to the knobs 3 k except that the knobs 59 may be arranged in a co-axial configuration instead of a triangular configuration and each knob 59 and have a diameter ranging between thirty and fifty percent of a diameter of the back face of the substrate 56. The second SCOS may include the knobs 59 and a pair of complementary dimples (not shown) formed in either pocket 4, 34 for mating therewith.

Alternatively, the second SCOS may be used with the third shaped cutter 50 instead of the SCOS 3.

FIG. 11C illustrates a knob 61 of a third SCOS, according to another embodiment of the present disclosure. The third SCOS may used with a fifth shaped cutter 60 which is similar to the fourth shaped cutter 54. The fifth shaped cutter 60 may include the non-planar cutting table 55 mounted to a cylindrical substrate 62. The substrate 62 may include the single knob 61 mounted to the back face of the substrate. The knob 61 may be similar to the knobs 3 k except for being singular and having a diameter ranging between thirty and seventy-five percent of a diameter of the back face of the substrate 62. The third SCOS may include the knob 61 and a complementary dimple (not shown) formed in either pocket 4, 34 for mating therewith.

FIG. 11D illustrates a sixth shaped cutter 63 for use with the SCOS 3, according to another embodiment of the present disclosure. The sixth shaped cutter 63 may be similar to the second shaped cutter 43 except for having six ribs and six bases instead of three. The sixth shaped cutter may have the knobs 3 k mounted to a back face of a substrate thereof or may have six knobs formed on the substrate back face. A fourth SCOS (not shown) may include the six knobs and a complementary set of six dimples (not shown) formed in either pocket 4, 34 for mating therewith

Alternatively, the sixth shaped cutter may have any N number of ribs and bases and have N number of knobs mounted to the back face of a substrate thereof, where N is an integer ranging between three and six. The SCOS for use with the alternative sixth shaped cutter may include the N knobs and a complementary set of N dimples formed in either pocket 4, 34 for mating therewith.

Advantageously, as compared to one or more of the prior art references discussed above, the SCOS 3 is self-guiding, whereas the prior art references require precise alignment to engage, thereby slowing down the brazing of the cutters into the pockets. Further, the SCOS 3 significantly increases bonding area for the second braze material, whereas the prior art references do not. Further, the dimples 3 d are simple shapes to form in either of the pockets 4, 34 whereas the shapes of the prior art references can be cumbersome to form in the pockets. Further, the precision of the dimples 3 d can be rough, whereas, the prior art references require precise receptacles in the pockets. Further, the robustness of the knobs 3 k resist damage due to rough handling of the cutters during brazing into the pockets 4, 34, whereas, the shapes of the prior art references can be quite fragile.

While the foregoing is directed to embodiments of the present disclosure, other and further embodiments of the disclosure may be devised without departing from the basic scope thereof, and the scope of the invention is determined by the claims that follow. 

1. A bit for drilling a wellbore, comprising: a shank having a coupling formed at an upper end thereof; a body mounted to a lower end of the shank; and a cutting face forming a lower end of the bit and comprising: a blade protruding from the body; a cutter comprising: a substrate mounted in a pocket formed in the blade; and a cutting table made from a superhard material, mounted to the substrate, and having a non-planar working face with a cutting feature; and a cutter orienting system, comprising: a knob mounted to or formed on a back face of the substrate; and a dimple formed in a back wall of the pocket and engaged with the knob, wherein the dimple and the knob are positioned relative to the cutting feature to orient the cutting feature to an operative position.
 2. The bit of claim 1, wherein: the cutting feature is a protruding ridge, the working face has a plurality of protruding ridges spaced therearound, the cutter orienting system comprises a knob and a dimple for each ridge, the knobs are spaced around the back face of the substrate, and each knob is angularly located opposite from the respective ridge.
 3. The bit of claim 1, wherein: the working face is concave, and the cutting feature is an axis of the cutting table.
 4. The bit of claim 1, wherein the cutting feature is an operative portion of a protruding ridge.
 5. The bit of claim 1, wherein the knob is hemi-spherical.
 6. The bit of claim 5, wherein a diameter of the knob ranges between 25 percent and 75 percent of a diameter of the back face of the substrate.
 7. The bit of claim 5, wherein the dimple is hemi-spherical.
 8. The bit of claim 1, wherein: the knob is mounted to the back face of the substrate by a first braze material, the cutter is mounted in the pocket by a second braze material, and a liquidus temperature of the first braze material is greater than a liquidus temperature of the second braze material.
 9. The bit of claim 8, wherein the knob is made from a different material than the substrate.
 10. The bit of claim 1, wherein: the pocket is formed in a leading edge of the blade, and the operative position is such that the cutting feature is perpendicular to a projection of the leading edge through the pocket.
 11. The bit of claim 1, wherein: the bit further comprises a gage section forming an outer portion of the bit, and the blade extends from a center of the cutting face to the gage section. 